Carton with a side opening



FIG. 1 is a perspective view of a carton with a side opening; and,

FIG. 2 is a front elevation thereof.

The dash-dot-dash lines adjacent to the shaded areas define the bounds of the claimed design.

The broken lines showing of cartons are for illustrative purpose only and form no part of the claimed design. 

The ornamental design for a carton with a side opening, as shown and described. 